Portable calculator



FIG. 1 is a perspective view taken from the front, top and right of a portable calculator showing my new design;

FIG. 2 is a perspective view taken from rear, top and left thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a right side elevational view thereof. 

The ornamental design for a portable calculator, substantially as shown and described. 